Effective voluntary, neural control of prosthetic limbs may require sensory feedback that is suitably integrated into sensorimotor systems mediating fine motor skills and discriminative touch. This research plan is based on the assumption that the rational design of artificial sensors incorporated into sensorimotor prosthetic devices depends on an understanding - and exploitation - of the function of central somatosensory circuits that provide relevant, appropriately processed information to motor cortex. In rats, cortically processed somatosensory information is critically important for the control of whisker movements during vibrissal-based active touch. Here we take advantage of the large and growing knowledge base about the organization and function of the rodent whisker system. The principal goal of this research plan is to develop a model system in rats for investigating neural sensorimotor prostheses. Intracranial electrical stimulation keyed to external sensor activity will be used as surrogate sensory stimuli that direct voluntary whisker movements. Rats will be trained to control whisker movements on the basis of surrogate sensory feedback signals delivered into the central nervous system by electrical stimulation of the somatosensory thalamus. Successful outcomes would demonstrate that 1) electrical stimulation of central, somatosensory pathways is an effective signal for regulating voluntary, fine motor behavior, 2) such stimuli can serve as surrogate signals for contact-mediated active touch, and 3) an external, sensory prosthesis can be incorporated into voluntary, sensorimotor control. Future studies could employ similar approaches to investigate motor cortical activity and its use in controlling a prosthetic whisker, analogous to neural control of robotic arms in primates. Combining this with the sensory approaches developed in the present research plan would complete a prosthetic sensorimotor loop that can mediate discriminative active touch. PUBLIC HEALTH RELEVANCE This research plan is based on the assumption that the rational design of artificial sensors incorporated into sensorimotor prosthetic devices depends on an understanding - and exploitation - of the function of central somatosensory circuits that provide relevant, appropriately processed information to motor cortex. The principal goal of this R21 application is to develop an experimental approach in rats for evaluating the use of artificial sensori-neural feedback for fine motor control during active touch.